1. Field of the Invention
The invention relates to a tensioning device for the cable pull of a cable-pull window opener, in particular for motor vehicles, the tensioning device being accommodated in a driver of the window pane, the driver being along a guide rail and being fixedly connectable to one end of the cable pull, and the tensioning device comprising a spring-loaded directional locking mechanism which can be connected to the other end of the cable pull.
2. Description of the Related Art
A tensioning device of this type is disclosed, for example, in DE 3829680C2, which is included by express reference in the disclosure contents of the present application. This publication discloses a tensioning device for the cable pull of a cable-pull window opener, the tensioning device being accommodated in a driver which is pulled up and down on a guide rail by means of a cable wrapped around a driving drum, one cable end being fixedly connected to the driver and the other cable end being connected to the driver via a directional locking mechanism. The directional locking mechanism consists of a toothed strip on the driver and a part which can be displaced relative to the toothed strip, engages with a tooth into the toothed strip and to which the other cable end is coupled. To compensate for cable stretching between the driver and the displaceable part a compression spring is provided which constantly strives to push the displaceable part having the cable end coupled to it relative to the driver in a cable-tightening direction. A second spring which is stronger than the compression spring is inserted between the displaceable part and the cable end coupled to it. By this means, in the prior art the object is achieved of specifying a tensioning device in which the cable slack produced by excessive application of force on the driving crank is compensated for separately in that during the next downwards movement of the window pane, this cable slack is again taken up in the mechanism in a normal manner while the actual tensioning device is only actuated if there is an actual stretching of the cable.
Another window opener is disclosed in DE 2750904C2. The window opener directs [sic] a cable which is guided in loop form in a Bowden-cable casing, can be unwound and wound up in both directions on a cable drum by means of a driving device and bears a driver which is connected to the window and is guided along a guide rail. Furthermore, a tensioning element is provided which compensates for the length changes occurring as a result of the cable being stressed. The tensioning element has a locking mechanism which inhibits movement of the tensioning element in the slackening direction. The disclosure contents of this publication is also included by express reference in the present application.
The known devices for adjusting the length of the cable pull are structurally of complex design and have an overall form of large proportions. Also, the known tensioning devices are able to be fitted only in a manner which takes up a relatively large amount of time.
In contrast, the invention is based on the object of developing a tensioning device having the features mentioned at the beginning to such an extent that the design and the overall size, and also the fitting of the tensioning device, is [sic] simplified.